Dual role of Sb ions as electron traps and hole traps in photorefractive Sn sub(2) P sub(2) S sub(6) crystals

• Published in: Optical materials express Vol. 6; no. 12; pp. 3992 - 3999
• Main Authors: Kananen, B E, Golden, E M, Basun, S A, Evans, D R, Grabar, A A, Stoika, I M, McClory, J W, Giles, N C, Halliburton, L E
• Format: Journal Article
• Language: English
• Published: 01-12-2016
• Subjects: Antimony; Crystal defects; Crystals; Electron paramagnetic resonance; Hole traps; Lasers; Photorefractivity; Vacancies
• ISSN: 2159-3930; 2159-3930
• DOI: 10.1364/OME.6.003992

Doping photorefractive single crystals of Sn sub(2) P sub(2) S sub(6) with antimony introduces both electron and hole traps. In as-grown crystals, Sb super(3+)(5s super(2) ions replace Sn super(2+) ions. These Sb super(3+) ions are either isolated (with no nearby perturbing defects) or they have a charge-compensating Sn super(2+) vacancy at a nearest-neighbor Sn site. When illuminated with 633 nm laser light, isolated Sb super(3+) ions trap electrons and become Sb super(2+)(5s super(2)5p super(1) ions. In contrast, Sb super(3+) ions with an adjacent Sn vacancy trap holes during illumination. The hole is primarily localized on the (P sub(2) S sub(6)) super(4-) anionic unit next to the Sb super(3+) ion and Sn super(2+) vacancy. These trapped electrons and holes are thermally stable below ~200 K, and they are observed with electron paramagnetic resonance (EPR) at temperatures below 150 K. Resolved hyperfine interactions with super(31) P, super(121) Sb, and super(123) Sb nuclei are used to establish the defect models.